Comparison of the morphological aspects of
Currently, ten genotypes (G1-G10) of Echinococcus Sensu Lato have been explicitly identified on the basis of taxonomic criteria. These include morphometric keys, host specificity, geographical distribution, phylogenetic analysis and genome mapping. However, a few emergent species of genus Echinococcus have been indigenously confirmed in some autonomous regions of Tibet plateau and Africa where there is little known about their biological aspects and potential pathogenicity in intermediate and definitive hosts. This chapter is focused on the parasite history, life cycle, phenotypic aspects, epidemiology, zoonotic potential and phylogeny relationship of two enigmatic parasites namely: Echinococcus shiquicus and Echinococcus felidis. This aims to provide a better understanding of their taxonomic status, public health problems and biological features in the mentioned regions.
- Echinococcus shiquicus
- Echinococcus felidis
- Biological Aspects
- Phylogenetic traits
Currently, ten genotypes (G1-G10) of
2.1. History, morphology and biology
Afterward, based on taxonomic criteria including morphology, host specificity, molecular characters and geographical distribution was considered as a new species of
The sylvatic cycle of
The adult worms of
The metacestode stage of
|Body Length (mm)||1.3 -1.7||2.0–11.0||1.2– 4.5|
|Number of segments||2–3||2– 7||2–6|
large hook on the rostellum (microns)
|20.0– 23.0||25.0– 49.0||24.9– 34.0|
small hook on the rostellum (microns)
|16.0–17.0||17.0– 31.0||20.4– 31.0|
|Number of testicles||12–20||25– 80||16– 35|
The concomitant (dual) infections of
Although, no human infection of
Therefore, additional studies are required to survey the possibility of human infections which can be employed in animal's models by serial passages using diagnostic antigens. The biological aspects of
||Africa||Warthog (possibly zebra, wildebeest,
bush pig, buffalo, various antelope, giraffe,
2.2. The evolutionary markers and molecular approaches in identifying
The evolution in
Mutations occurred in the non-synonymous sites (called replacement sites because mutations at these sites lead to a change in the protein sequence) and the synonymous sites (called silent sites because mutations there do not lead to a change in the protein sequence) [6, 7].
It is worth noting that the nucleotide substitutions (Transition/Tranversion models) and/or indels (insertion or deletion) in the first and second positions of codons usually lead to create a new species/strain, which directly affect the frame shift of amino acids in case of any amino acid shifting or changing protein functionality while, changing in third position of codons (wobble site) is frequently leaded to creating novel haplotypes [8–11].
To date, the status of
It is important that the employing extra nuclear (mitochondrial) markers with low copy numbers and high variation characteristics are able to identify the unknown species/strains even haplotypes in exceptional regions where several intermediate hosts are circulating unequivocally .
2.3. Phylogenetic findings
Sequencing, phylogenetic and bioinformatics' analyses of mtDNA  and nuclear DNA  revealed that
The molecular characterization of
This heterogeneity can be elucidated by description of three assumptions. First: presence of two turnover mechanisms, namely; unequal crossing over/transposition and slippage in the sequence length of parasite . Second: lack of any bottleneck effects after its ancestor had been isolated on the Tibetan Plateau by colonizing alpine mammals (genetic drift or founder effect) . And third: the long term geographic segregation into the plateau.
In a study, three polymerase chain reaction (PCR) assays based on the amplification of a fragment within the NADH dehydrogenase subunit 1 (ND1) mitochondrial gene have been optimized for the detection of
However, the taxonomic position, human infection, intermediate hosts and DNA profile of enigmatic ‘lion strain’ from Africa  has been unknown due to unavailability of suitable isolates.
3.2. History and biology
Many records of this parasite remained unidentified from a large variety of African mammals, due to the lack of diagnostic criteria, mainly genetic characterization and the misdiagnosis with the sympatric
Echinococcosis is a high public health priority in the endemic areas of the world especially Africa, where more than one species of intermediate host is present and there is the possibility of interaction between cycles of transmission. Therefore the concomitant infections of
The explicit status of
The felids act as definitive hosts for enigmatic ‘lion strain’ however, It is still unclear which of the sympatric wild ungulates serve as intermediate hosts in life cycle of
3.3. Phylogenetic findings in
Based on sequences of mitochondrial genes for cytochrome c oxidase subunit 1 (cox1), NADH dehydrogenase subunit 1 (nad1), cytochrome b (cob), rRNA (rrn), and nuclear genes for elongation factor 1 alpha (ef1a), ezrin-radixin-moesin (ERM)-like protein (elp) and
Considering the assumption, ancestral lineage of
The tree was reconstructed by the maximum likelihood method and Kimura-2 parameter model.
At this time, there are no valid data on the pathogenicity of
On the other hand, information about intermediate hosts of this parasite is still unknown, even though a hydatid cyst was identified as
In the past decade,
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